Layered photoconductors that can be selected for various copying and printing processes are known. Each of the layers of the photoconductors serves a certain function, such as generating charges, and transporting charges. This raises a number of considerations because the components of these layers can, for example, influence the photoconductor properties.
Multilayered photoconductors can comprise a supporting substrate, an electrically conductive layer, an optional charge blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer, and an optional protective or overcoating layer. These multilayered photoreceptors can be provided in any of various forms, such as flexible belts, rigid drums, and flexible scrolls. Flexible photoconductor belts may either be seamed or seamless. An anticurl layer may also be coated on the back side of the flexible substrate support, or the side or surface opposite to the electrically active layers, to achieve the desired photoreceptor belt flatness.
A number of photoconductors exhibit mechanical failures, such as frictional abrasion, undesirable wear characteristics, and significant surface cracking. Photoconductor surface cracking is primarily induced because of the dynamic fatigue of the belt flexing over the supporting rollers of a machine belt support module or cracking can be caused by exposure to airborne chemical contaminants as the photoconductor segments directly bend over the rollers after periods of photoconductor belt non-use during machine idling. These chemical contaminants include solvent vapors and corona species emitted by machine charging subsystems. Surface cracking can also be exacerbated by the combination of the effects provided by fatigue belt flexing and airborne chemical exposure. In turn, photoconductor cracking can manifest itself as printout defects that seriously impact copy quality. Further, surface cracking may require the untimely replacement of photoconductors at significant costs. While used photoconductor components can be partially recycled, there continues to be added costs and potential environmental hazards when recycling.
Also known are photoconductors that have a minimum or lack of resistance to abrasion from dust, charging rolls, toner, and carrier. Additionally, the surface layers of photoconductors are subject to scratches, which decrease their lifetime, and in xerographic imaging systems adversely affect the quality of the developed images.
Thus, there is a need for photoconductors with excellent or acceptable mechanical characteristics, especially in xerographic systems where biased charging rolls (BCR) are used.
Further, there is a need for photoconductors that exhibit minimum wear or possess wear resistance characteristics, especially in xerographic processes and machines.
Additionally, there is a need for polymeric binders that can effectively have dispersed therein a charge transport compound and a second binder, and which polymeric binders are compatible with conventional polymer binders used in charge transport layers, such as polycarbonates.
Photoconductors with excellent cyclic characteristics and stable electrical properties, stable long term cycling, minimal charge deficient spots (CDS), and acceptable lateral charge migration (LCM) characteristics, such as excellent LCM resistance, are also desirable.
These and other needs are believed to be achievable in embodiments with the photoconductors disclosed herein.